Tfi 23 
.fi35 



NUMBER 23 

OCCASIONAL PAPERS 

ENGINEER SCHOOL 

UNITED STATES ARMY 



EXTRACTS 



FROM 



Reports Upon Technical Details 

of Engineering Works 

1906 



WASHINGTON BARRACKS, D. C. 

PRESS OF THE ENGINEER SCHOOL 

1907 



/iOflogfapU 



NUMBER 23 

OCCASIONAL PAPERS 

L.S. ENGINEER SCHOOL 

UNITED STATES ARMY 



EXTRACTS 



FROM 



Reports Upon Technical Details 

of Engineering Works 

1906 



WASHINGTON BARRACKS, D. C. 

PRESS OF THE ENGINEER SCHOOL 

1907 



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MAY 18 1907 

D.ofa 



I • • •• 
• • • " 



Defenses of the Coast of Maine and 
New Hampshire. 

(Officer in charge, Lieut. Col. W. M. Black, Corps of Engineers.) 

The construction methods detailed in the technical report for 1905 for 
the traverse roofs of the 6-inch batteries have proved satisfactory. The 
only improvement made has been a provision for channel iron gutters in 
recesses in the magazine ceilings directly beneath the planes of weakness 
of the roof blocks. The exposed surfaces of all concrete blocks are now 
finished with the wood float only. When surfaces are trowelled smooth, 
a skin of cement is brought to the top. This has a larger coefficient of 
expansion than the concrete, and a network of disfiguring hair cracks is 
formed on the surface. Under certain conditions this skin may flake off. 

The waterproof pavements for the loading platforms described in page 
3006 have proved satisfactory to date. When soft burned porous tile are 
kept saturated with water and exposed to alternate freezing and thawing 
under the severe conditions of the Maine climate, they are broken up. In 
the latest work, tile laid in positions subject to such exposure have been 
boiled in paraffine before placing. Each tile thus treated took up about 
one-half pound of paraffine, and subsequent tests showed that the treated 
tiles had become non-absorbent. 

In some of the older batteries the mass concrete of the traverses and 
parapets is \ery porous. In these cases annoying leaks are sometimes 
formed in the galleries below the waterproof pavements by water from 
the porous concrete entering the gallery roof supporting the pavement 
where this abuts against the mass. The water enters below the water- 
proofing and follows along the sides of the supporting I-beams for some 
distance before appearing on the surface. The conditions have been 
helped by a narrow groove cut from below into the ceiling, outside of the 
mass and parallel to its face. This intercepts a part of the water, but to 
stop the leak the water must be kept out of the concrete masses. Experi- 
ments looking to this end have been fairly successful. 

Waterproofing Exterior Surfaces. — In one of the older batteries the gal- 
leries in the traverse were very wet. A coat of Staso cement applied on 
the surface, in conjunction with the Staso compound in the larger cracks, 
which were widened to receive it, made a decided improvement. The 



amount of surface covered was insufficient to stop all leaks, and further 
work remains to be done. 

In another battery, where expansion cracks had formed in the loading 
platform and caused leaks in the galleries beneath, half-inch expansion 
joints were formed 10 feet apart and filled with the elastic Staso compound, 
and the smaller intermediate cracks were filled with the non-elastic glycerine 
and litharge cement. This was also fairly successful. This cement bonds 
strongly with the concrete. 

Coal tar pitch applied with a brush while melted was also tried success- 
fully on the top of the traverses, in the same manner as in the New York 
district. The black color of the coal tar pitch and the red color of the 
Staso are disadvantageous, in making the superior slopes more conspicuous 
as seen from the sea. 

Another leaking traverse was treated on its top surface with paraffine 
after the larger cracks had been filled with Webster's cement. A mixture 
of 1 part white paraffine wax and 2 parts kerosene heated to a temperature 
of 212 was applied to the surface with a brush. The mixture cooled at 
once and left a thin skin on the surface of the concrete. This was then 
gone over with a hot smoothing iron, such as is used for asphalt pave- 
ments, and the paraffine largely disappeared into the concrete. Eighty- 
eight pounds of paraffine were used on 2,400 square feet of surface at a 
cost of $0,014 per square foot. The work was done in November, 1905, 
and resulted in a great reduction of the leakage into the traverse rooms. 
Another application of the paraffine being made now seems to show that 
the coat applied last fall has penetrated the concrete sufficiently to permit 
the absorption of more paraffine. The application of the paraffine darkens 
the color to that of wet concrete. 

Elaterite cement paint, manufactured by the Elaterite Paint and Manu- 
facturing Co., of Des Moines, Iowa, has been given a short test on the 
surface of a leaky gutter sunk in the top of a traverse. It spreads thinly 
on the concrete, adheres strongly to it and renders it waterproof. Should 
it stand the test of time it is a very valuable waterproofing material. Its 
color is black. 

A mixture by volume of 3 parts litharge, 1 part glycerine, 48 parts 
Portland cement and 48 parts sand, makes a strongly adherent and dense 
plaster, which has been used with some success in the ceiling of a leaky 
traverse room, through which water had been percolating freely. A 
groove cut in the ceiling in the side from which the greater part of the 
water apparently came afforded a drain, and the plaster coat prevented the 
general percolation through the ceiling. The plaster bonded well with 



m\\ 121907 
U. OF D. 



the concrete without other aid than cleaning the surface with a wire brush. 
It has been in too short a time to be tested thoroughly. 

In one of the mortar batteries a stone filling had been placed under the 
loading platform, without adequate drainage. This filling formed a reser- 
voir for water which froze in the winter and raised the blocks of the pave- 
ment, which in summer fell back into place. A series of holes was drilled 
through the pavement during the past summer and cement grout was 
forced in by gravity. Levels taken during the past winter showed a 
marked improvement. Further treatment of the same kind will be made 
during the present season. 

The office test of sheet copper reported on page 3004 of the annual 
report of the Chief of Engineers for 1905 was continued until July 14, 
1906. The copper in box form was removed from its supporting wood 
cover, emptied and cleaned. The bottom of the box was bright and 
clean. Toward the top of the sand and above it the copper was heavily 
coated with the green and bluish salts. The back of the plate, where in 
contact with the wet wood of the cover, was also heavily coated and pitted 
half way through, the pits being filled with red copper oxide. On weighing 
the copper it was found to have lost 2.04 per centum in weight. The 
plate suspended in air was heavily coated with the greenish salts. After 
cleaning, it was found to have lost 6.8 per centum of its weight. 

Auxiliary Buildings. — Several buildings pertaining to the mine defense 
have been constructed during the year, with steel or wood frames covered 
and lined with cement plaster reinforced with expanded metal. The 
frames of these buildings are constructed in the usual manner, excepting 
that the studding is spaced 12 inches center to center. On the studding 
is stretched (with staples for wood and by wiring for steel) expanded 
metal (No. 18, one-half inch mesh) which with wood studding is furred 
out by one-quarter inch steel rods. Between the studding and one-half 
to three-quarters of an inch in rear of the expanded metal, boards are set 
up temporarily, filling the spaces. The plaster coat is then placed and 
pressed well in against the boards, working from the bottom up. This 
is placed in two coats, the second being placed as soon as the first coat 
has begun to set, but before it has set enough to form a plane of weak- 
ness. The finish is given with a wood float. The total thickness of the 
plaster is made about 2 inches. After the plaster is set, the boards are 
removed and any imperfections in the back of the slab are filled. Parker's 
metal corner strips are used in exterior corners. The plaster is composed 
of 1 part lime putty of the consistency of thick cream (the lime having 
been slaked and the putty made ten days before time for using), 3 parts 
cement, and 8 parts sand. No hair is used. The plaster must be mixed 



rather stiff. When set, this plaster is hard and dense and has withstood 
the winter without injury. To form a backing for the inside plaster, a 
heavy, reasonably waterproof building paper (like 3-ply Raven) is placed 
in the studding and expanded metal (B lath) is stretched over this. The 
inside slab is made about 1 inch thickness. A small quantity of calcium 
plaster was added to the cement plaster for ceiling work and for running 
cornice and mouldings. All hollow spaces in the walls and ceilings must 
be connected with the air outside or within the building by holes through 
the plaster, to lessen the strain on the plaster slabs caused by the air pres- 
sure produced by the blasts of the guns. Observations made during target 
practice show a marked air movement through the holes when the guns 
are fired. 

In two of the buildings the roofs were made of reinforced concrete 
slabs made like the outside sheathing, 2 to 3 inches thick, running from 
the ridge to the eaves, and provided with expansion joints. These roofs 
have been in place for about nine months and are tight. 

A tin roof was used in a double observation station. For sound 
deadening a layer of "Florian" sound-deadening felt and one layer of 
National " deadening felt were placed between the tin and the roof 
sheathing. This combination seems efficacious. 

The water fixtures for the closets and wash-bowls of the auxiliary 
buildings are of the non-freezing type, with automatic drainage. The 
faucets of the wash-bowls are operated by pedals in the f^oor. All valves 
and traps are placed below the frost line in a small cement vault, which 
can be filled in winter with fresh horse manure. 

Owing to the conditions at Portland, the search lights of the forts have 
to be elevated. They are placed on towers in the rear of the line of 
observation stations and are elevated sufficiently to prevent the illumina- 
tion of the batteries in the foreground. In one of the forts, where the 
available site is restricted, the 36-inch observing light is mounted on the 
same tower as the 60-inch search light and is 13 feet below it. This 
arrangement is satisfactory. It is easy to prevent the beams from cross- 
ing, and also to prevent the lights from blanketing the observers in the 
stations and in the batteries. The tower is cf temporary character and 
built as shown in the accompanying sketch. The 60-inch light is on a 
platform, raised and lowered by a hand winch. 




"'=^^~ 



f/ofrizoNTAL Section on A-B 



MoatZQriTA.1. .STCTVO/v ow C-I?. 



Defenses at Eastern Entrance to 
Long Island Sound. 

(Officer in charge, Lieut. Col. C. F. Pcwell, Corps of Engineers.) 
PREVENTION OF LEAKAGE AT EMPLACEMENT ROOMS. 

Sheet copper waterproof course, as described in my technical report for 
1903, annual report, Chief of Engineers, page 2388, has so far given satis- 
faction. 

WATERPROOF COATINGS AND SEAM FILLERS. 

Observations and further experiments with working samples of such 
material as mentioned in technical report for 1904, annual report of the 
Chief of Engineers, page 3718, and in Eighth Supplement to Mimeo- 
graph 61, were continued. The coating of Elliot's Roof Leak on con- 
crete superior slopes, which appeared to be excellent for several months, 
begun to scale under wear after a year. A new sample of Hydrolene B, 
melting point 200°, and Staso liquid cement, applied March, 1905, on 
cold surfaces, wear well to the present time; the sanded better than the 
unsanded parts. Each penetrates and adheres to the concrete. Staso has 
an Indian red color fading on exposure; Hydrolene B has a fast black 
color. Nicolite No. 1 and No. 2, and Szerelmey did not appear so suit- 
able. Linseed oil waterproofing, described in the report of Chief of 
Engineers named above, has been extensively used in this district and is 
regarded favorably. 

Staso Compound No. 5 was placed in a vertical joint 1 inch wide and 
2 inches deep, March 14, and in horizontal joints February 2, 1905. It 
showed a tendency to run in warm weather and bulge out of the joint; 
it is pliable and easily worked back. When examined, September 6, 1905, 
the surface of the compound was full of fine cracks, but the material 
adhered strongly to the concrete. Webster's elastic cement was con- 
tinued to be used extensively in wide vertical and horizontal joints and 
cracks with good results. 

MEASURES AGAINST CONDENSATION. 

Linings. — The Oregon cedar ceiling, referred to in technical part of 
annual report of the Chief of Engineers, 1904, page 3717, has shown this 



late summer a very small area of fine dry mould on the cedar, at the 
front of the storeroom, together with a marked dampness on the con- 
crete floor; at a magazine room of this 3-inch Fort H. G. Wright bat- 
tery, where the front half of the ceiling is Oregon cedar and the other 
half white pine, dry mould appeared at the sapwood of the pine, but 
none at all on the cedar. No dampness on either wood, neither at the 
porous brick lining at walls, was observed; the concrete floor of the 
magazine named, near the front of the room, was slightly damp. 

Linings made at new batteries at Fort Michie are of porous brick, 
porous tile, and porous mortar, as described in the annual report, same 
page, named above. Careful observations here as to condensation were 
made at frequent times since early April, 1905, by Junior Engineer 
Hunter. His report records a very general absence of condensation at 
the linings except at non-porous mortar joints; that condensation on 
concrete or metal surfaces quickly disappeared when rooms were opened 
at times of clear and dry weather, and even that such moisture was 
noticed in one case to disappear over night of good weather, although 
the battery was tightly closed. In summing up conclusions he places 
the different linings used in order of effectiveness as: 

Hollow porous tile. 

Porous brick (Infusorial Earth Company's). 
Poious mortar, one-half inch coat. 
Rough-finished concrete. 
Smooth-finished concrete. 

At F ort Terry, new batteries of one group have large vertical ventilator- 
openings, 12 inches diameter at front of rooms, or 12 inches by 18 inches 
at powder passage, and good porous brick linings. At another group the 
brick of linings are not so good and the ventilation not so free. From 
reports of observations at time to time by Junior Engineer F. W. LaForge, 
it appears that while dampness from condensation is very small throughout, 
the rooms of the first group are on the whole, but not entirely, somewhat 
freer from it than those of the second group. 

Fan Circulation of Hot Air. — Subsequent to the application of this 
means of reducing or preventing condensation at emplacement rooms, 
described in annual report of the Chief of Engineers, 1904, page 2713, the 
second battery there noted was thoroughly dried and heated by this 
method and in late September, 1904. Previous to its first hot-air treat- 
ment, this battery had shown prolific condensation. Another battery, 
adjacent, of the same type and built about the same time, was much more 
dry in 1904 than the one denominated as the second battery. During 



the past condensation season, however, the com'parative results as to con- 
densation at these two batteries have been reversed, so that the much 
drier battery this year was the one which had been so thoroughly dried 
and heated last year. That this continuation for several months of a 
decided amelioration of condensation was caused by three applications of 
two hours each of the hot-air treatment seems a fair conclusion. 

CONCRETE FEATURES AT A TORPEDO STOREHOUSE. 

This structure is of red brick, about 32 feet wide by 195 feet long and 
two stories high. It was first thought to use granite trimmings, but the 
cost of the stone, even in this location of granite quarries, was considered 
too high and recourse was had to concrete for lintels, sills, and water-table. 
This construction proved so satisfactory that concrete corners were added, 
and, later, a concrete cornice was built in place instead of a wooden one, 
at the suggestion of Assistant Engineer G. W. Freeman. Such cornice 
strengthens the roof truss, is fireproof, and improves the appearance of 
the building. 

^ :^ jji :^ :^ ^ :Jt 



Correspondence About Cedar Linings of 
Magazines in Puget Sound District. 

(Officers in charge, Maj. John Millis and Lieut. F. A. Pope, Corps of Engineers.) 

United States Engineer Office, 

Seattle, Wash., February lo, IQOJ 
Brig. Gen. A. Mackenzie, 

Chief of Engineers, U. S. A., Washington, D. C. 

General: 

I have the honor to request to be advised as early as may be practicable 
of the conclusions of the Board on percolation and dampness in maga- 
zines of defensive works so far as same may be applicable to this district. 

Very respectfully, your obedient servant, 

John Millis, 
Major, Corps of Engineers, U. S. A. 



[1st Indorsement.] 

War Department, 
Office of the Chief of Engineers, 

Washington, February 20, 1905. 

Respectfully referred to Lieut. Col. C. F. Powell, Corps of Engineers, 
with request for an early rendition of this most important report, in 
order that the best application of funds under the pending fortification 
bill may be made by this oflice. 

^ >jC >j< ^ ^ :^ jjt 

By command of Brig. Gen. Mackenzie: 

Frederic V. Abbot, 

Major, Corps of Engineers. 



[2d Indorsement.] 

U. S. Engineer Office, 
New London, Conn., March 3, iQOj. 

Respectfully returned to the Chief of Engineers, U. S. A. 

The report may be expected on or very shortly after the 25th inst. 

It may be remarked that condensation at the Puget Sound district is 
little and can be prevented by small ventilation or heating from oil or 
other stoves at suitable times. Some of the emplacement rooms there 



10 

are, however, quite damp from leakage and require treatment at the 
exterior or room linings. 

?|C #^ ?jC ?jC ?jC ?j^ *q> 

I suggest that this method be tried as early as practicable at the Puget 
Sound district, where cedar is readily obtained at moderate cost, and for 
the special purpose of aiding to determine the least thickness of cedar 
needed for supporting the sheet copper between bolts and making a 
rigid enough structure to stand the ordinary service. 

^I> ^^ v^ sf^ v]^ ^I^ ^1^ 

Chas. F. Powell, 
Lieut. Col., Corps of Engineers. 



[3d Indorsement.] 

War Department, 
Office of the Chief of Engineers, 

Washington, March 8, iQOj. 

Respectfully returned to Major Millis, inviting attention to the 
preceding indorsement. 

Two rooms should be lined at once as suggested, accurate account 
being kept of actual costs. 

To be returned with report of costs as soon as the work is completed. 

In the report enough details should be given as to how superintendence, 

contingencies, etc., are computed, and what rates of pay are used, to 

make it possible for other officers to make reliable local estimates. 

By command of Brig. Gen. Mackenzie: 

Frederic V. Abbot, 
Major, Corps of Engineers. 



[4th Indorsement.] 

U. S. Engineer Office, 
Seattle, Wash., March /, igod. 

Respectfully returned to the Chief of Engineers, U. S. A. 

Two magazines, one in emplacement No. 1 and one in emplacement 
No. 3, have been lined ar a cost of $2,215.02, and payment has been 
made from the allotment of June 21 and July 5, 1904, act of April 21, 
1904, from the appropriation for Preservation and Repair of Fortifications. 

A tracing showing method of lining the magazines and a report in 

detail of the cost are sent herewith. 

F. A. Pope, 

1st Lieut, f Corps of Engineers. 



11 

STATEMENT OF COST OF LINING POWDER MAGAZINES WITH 
COPPER AND CEDAR IN 10-INCH EMPLACEMENTS AT FORT 
CASEY, WASHINGTON. 

The two most leaky magazines were selected for treatment. The 
following remarks show condition of the magazines before lining. 
Emplacement No. l: 

Jan. 23, 1904 — General leaks all over roof, one-fourth inch water on floor in 

places. Leak around speaking tube. 
Mar. 9, 1904 — Floor wet. Dropping from ceiling. Doors open. 
Nov. 22, 1904— Leaking. 

Mar. 25, 1905 — Roof leaks; puddle on floor; leak at speaking tube. 
May 23, 1905 — Leaking badly south half ceiling and over doorway. 
Emplacement No. j: 

Jan. 23, 1904 — Pretty dry; condensation on roof and door. 

Mar. 9, 1904 — Dry and nice; doors open. 

Nov. 22, 1904— Leaking. 

Mar. 25, 1905 — Leaky roof near door. , 

May 23, 1905 — Ceiling leaking; also over doorway. 

These examinations were made after heavy continuous rains of some 
24 hours duration. 

No leaks have appeared to date through the new lining. 

The magazines are 13 feet 6 inches by 20 feet 6 inches, 8 feet high, 
and were built by contract in 1897—98. 

The drainage chamber is now ventilated by three openings, each 24 
inches by 24 inches through the interior walls. Room ventilation is 
given by apertures which have been cut in the iron doors controlled by 
shutters. 

Ventilation was entirely ignored in original construction. 

The best material obtainable has been used, placed by skilful men and 
no pains spared to make the job as nearly as possible perfect in all respects. 
It was done by day labor; commenced latter part of May, 1905, and 
finished early part of January, 1906. Owing to exigencies of other 
requirements and some waits for material, it was not practicable to prose- 
cute the work uninterruptedly. 

It was not at first designed to line the head-room over the door passage, 
but this was later found necessary, which has added somewhat to the cost. 

Itemized Statement of Cost. 
Superintendence : 

Proportionate salary Junior Engineer $16.50 

Proportionate salary Inspector, work and material 46.88 

Transportation of Engineer and Inspector 4.00 

$67.38 

Amount carried over $67.38 



12 

Itemized Statement of Cost — Continued. 

Amount brought forward ^ $67.38 

Plans: 

Office work, Draftsman $40.57 

Material .50 

41.07 

Cutting and Drilling Concrete (Cutting out 110 cubic feet con- 
crete and drilling 300 holes 1 inch by 4 inches deep): 

Laborers, at $2.00 per day $220.00 

Blacksmith at $3.00 per day 8.17 

Tool steel, 132 lbs 9.67 

237.84 

Finishing Concrete: 

Cement Worker at $4.00 per day $69.76 

Cement, 4 bbls., at $3.00 per bbl 12.00 

81.76 

Drain Pipes: 

Cutting and placing; pipe fitters, at $3.00 per day $20,44 

13 feet of 3-inch and 50 feet of 2-inch galv. wrought-iron 

pipe and fittings 15.00 

35.44 

Hardnvare: 

Brass bolts, sleeves and washers, per detail $274.54 

Galv. iron anchors 56.80 

Lead washers 12.00 

Galv. lag screws with galv. expansion shields 12.60 

50 lbs. galv. cut nails 3.00 

79 lbs. common iron 1.8S 

Labor placing hardware, etc. 118.45 

479.27 

Copper Work: 

2,263 lbs. 16 oz. cold rolled sheet copper, 36 inches by 96 

inches, at 22>^ cents per lb $509.17 

40 lbs. solder at 20 cents per lb 8.00 

10 gals, gasoline 2.43 

1 qt. muriatic acid .10 

1 doz. hack-saw blades .60 

Coppersmith at $4.00 per day 233.15 

753.45 

Waterproofing: 

1,200 lbs. tar pitch at 1 cent per lb. $12.00 

Laborers, at $2.00 per day 22.25 

34.25 

Woodivork: 

6,792 lin. ft. >^-inch by 3-inch clear cedar. 

512 lin. ft. >^-inch by 2-inch clear cedar. 

336 lin. ft. l-inch by 2-inch clear cedar. 

16 lin. ft. 4-inch by 6-inch clear cedar. 

7,656 lin. ft. clear cedar at 14 cents per foot $108.24 

Amount carried over $108.24 $1,730.46 



13 

Itemized Statement of Cost— Continued. 

froodnvork — Continued: 

Amount brought forward $108.24 $1,730.46 

256 lin. ft. >^-inch by 2-inch clear spruce. 

168 lin. ft. 1-inch by 2-inch clear spruce. 

16 lin. ft. 4-inch by 6-inch clear spruce. 

440 lin. ft. clear spruce at 15 cents per foot 6.60 

Carpenters, at $3.00 per day 121.17 

236.01 

Painting: 

Material, 3 coats white paint $2.00 

Painter at $3.20 per day 28.50 

30.50 

Gratings: 

35 lbs. common iron $1.40 

Blacksmith at $3.00 per day 3.00 

Laborers, setting, at $2.00 per day 8 14 

12.54 

Cast Ventilators: 

6 standard frames and doors, at $13.33)^ $80.00 

6 padlocks, at $1.00 6.00 

Laborers, setting, at $2.00 per day 28.68 

114.68 

Door Ventilators: 

Material $0.80 

Blacksmith at $3.00 and helper at $2.00 48.87 

49.67 

Electric Wire Pipes: 

Pipe fitters, at $3.00 per day 9.98 

Incidentals : 

Kerosene $3.00 

Coal 2.00 

Glass for lanterns .30 

Sundry labor, cleaning up, team, etc. 25.88 

31.18 

Total cost for two magazines $2,215.02 

Average for one magazine 1,107.51 



River and Harbor Work in Detroit District. 

(Officer in charge, Colonel Chas. E. L. B. Davis, Corps of Engineers.) 
THE BATHOMETER. 

The bathometer described below was used in making the survey for 
the 22 and 25-foot channel from the lower end of Lake Huron to the 
upper end of the Detroit River. 

It was invented and developed by Mr. E. S. Wheeler, chief assistant 
engineer, and proved itself to be a very efficient sounding apparatus, par- 
ticularly as it gives a continuous profile of tHe river or lake bottom on a 
paper disk by means of a self-recording apparatus. 

A careful study of the records through Lake St. Clair showed an 
enlargement of the channel, which has probably taken place within the 
last ten years. Between 1894 and 1897 this channel was dredged to 20 
feet throughout its length, with the exception of about 2 miles, the total 
amount of material removed being about one and a half million cubic 
yards. The records showed that the dredged channel had been much 
widened and deepened, the portion where no dredging was done showing 
a well-marked channel. The total amount of material removed has been 
about three and a half million cubic yards, or two million more than had 
been dredged. The cross-sections show an irregular bottom from 800 to 
1,500 feet wide, following the sailing line from the lower end of the canal 
to the upper end of Grosse Point cut. This enlargement is undoubtedly 
due to the action of propellers of deep draft steamers. Before 1896 the 
maximum draft that could be carried through the locks at Sault Ste. 
Marie, Mich., was about 15 feet, not deep enough to have much effect 
on the bottom of Lake St. Clair, where the normal depth was about 19 
feet. In August, 1896, the Poe Lock was opened to commerce, which, 
with other improvements, increased the possible draft about 3 feet and 
brought the propellers of the heavily loaded steamers close to the bottom 
of Lake St. Clair, and it is probable that the enlargement began about 
this time and has continued at the rate of about 200,000 cubic yards 
annually. 

While the existence of this channel would have been revealed by the 
ordinary sounding-lead, its boundaries would not have been so sharply 
defined, and much closer soundings would have been necessary to have 
made as close estimates of the amount of material removed. 



16 

The instrument has certainly many obvious advantages and applications, 
and Mr. Wheeler will continue to perfect it. 



REPORT OF MR. E. S. WHEELER. 

The apparatus is called a "Bathometer." In its construction use has 
been made of the following principle: 

If air be forced through a tube the lower end of which is submerged in 
water, then the pressure of the air at the upper end will equal the pressure 
of the water at the lower end plus the pressure due to the frictional resist- 
ance of the air passing through the tube. If then the pressure of the air 
at the upper end of the tube and the frictional resistance are known, the 
pressure of the water at the lower end becomes known, and since the 
depth of water is a known function of the pressure, the depth is known. 

The essential parts of this bathometer are: First. A flexible tube 
weighted at one end so that it can be submerged, and branched at the 
other end so that an air pump and a pressure ^age or register can be 
attached. Second. An air tank and pump capable of forcing a continuous 
stream of air through the tube and out at its lower or submerged end. 
Third. A pressure gage that will measure separately the pressure due to 
the friction of the air passing through the tube, and the water pressure at 
the lower or submerged end. Fourth. A register that will record auto- 
matically and continuously the pressure at the upper end of the tube 
(expressed in feet) due to the depth of the submerged end. Plate 1 shows 
the apparatus with the parts assembled as they were used on the U. S. S. 
Hancock. The tube or sounding line is shown at G, Plate 1. It is made 
of a tube one-half inch in diameter with a bore of one-fourth inch. The 
tube is protected by a woven cotton covering, the warp of which is longi- 
tudinal or parallel to the rubber tube; this prevents excessive stretching 
and collapsing that might be the case if the warp was woven in a spiral 
around the rubber tube. The line used was four-ply, or had four con- 
centric coverings of cotton dipped in a preservative mixture, which gave 
the line a tensile strength of a little more than 1,000 pounds, and 
an exterior diameter of 0.85 of an inch. A cross-section is shown at 
Plate 1, R. Outside of the cotton there is a metal armor which serves 
the double purpose of weighting the submerged end and protecting the 
line from wear, as shown at H. The metal armor is made of short pieces 
of pipe about 1/^ inches long and % inch thick, which makes the outside 
diameter 1.35 inches. These short sections of pipe when made of iron 
are cast and chilled. Between the sections are rubber rings which serve 
the double purpose of keeping the line more flexible and preventing the 



17 

armor from slipping along the line. At the lower or submerged end of 
the line there is a check-valve which permits the unobstructed outward 
flow of the air and prevents the water from flowing back into the tube. 
The line used last season was 190 feet long and about 50 feet of the sub- 
merged end was armored with lead; this made a weight of about 130 
pounds. The air is first forced into the air tank D, Plate 1. When 
steam was available, a small Westinghouse air compressor C was used. 
At other times a hand pump* was employed. The air passes from the 
tank into the register A and A' and through the sounding line G. The 
register is automatic and is shown in detail on Plates 2 and 3. There is 
a paper disk or card I which is revolved by clockwork K. The index or 
pointer carries a fountain pen L, which leaves a continuous line or curve 
on the disk as it revolves under the pen. The pen is moved by the 
Bourdon tubes M. Several Bourdon tubes or "tube springs" are attached 
to one shaft in order to give enough force to move the pen over the sur- 
face of the paper disk. The register used last season had eight tube springs. 
The adjustments of the apparatus are made as follows: First. A suit- 
able scale is marked with circles on the paper disk L The levers N are 
then adjusted so that the pen will move a unit on the scale when the sub- 
merged end of the sounding line is changed a unit. This adjustment is 
tested by submerging the sounding line to a known depth and noting that 
the pen marks a corresponding depth on the scale. This adjustment 
when properly made is quite permanent. It is, however, not alone neces- 
sary that the pen should move over the proper distance, but it should point 
to the proper graduations on the scale. The second adjustment is to 
insure this result and may be called the adjustment for index error. When 
the open end of the sounding line is out of the water and the pen points 
to the zero of the scale, there is no index error. The three principle 
sources of index error are change of pressure in the air tank, dimensions 
of the sounding line, and area'of the aperture. The apparatus has there- 
fore been so arranged that while it is in use these three conditions can be 
kept so nearly constant that there is no appreciable index error. When 
not in use, the pen usually drops a little below the zero of the scale. The 
friction of the air in passing through the sounding line when its open end 
is out of water causes some pressure in the register. If air is admitted to 
the sounding line and register in exactly the right quantity, this frictional 
pressure will cause the pen to rise to the zero of the scale. If, now, the 
orifice between the tank and the register, the pressure in the tank, and the 
dimensions of che sounding line remain constant, the pen will remain at 
the zero of the scale, and the apparatus will be in adjustment. These 
three conditions are kept constant in the following manner : First. 1 he 



18 



pressure in the air tank is controlled by a governor. Second. The orifice 
between the tank and the register is a small circular hole in a diaphragm 
which is inserted in the connecting tube. This hole is sometimes jeweled 
to prevent rust or wear. The size is determined by repeated trials. The 
dimensions of the sounding line (length and diameter of the bore) are 
constant unless the line is changed, in which case a new adjustment for 
index error is made. With ordinary care the index error need not exceed 
two-tenths of a foot. The methods employed last season in the use of the 
'bathometer" were as follows : The work was done from the U. S. S. Han- 
cock. The depth of water was usually not more than 30 feet. Air was 
pumped into the tank so as to show a pressure of 70 pounds. All adjust- 
ments were carefully made. The sounding line was passed overboard 
and about 180 feet paid out. The steamer, running at the rate of about 
6 miles per hour, dragged the line over the area to be sounded. The 
register showed a correct cross-section of the bottom, as at P, Fig. 2. The 
lines of soundings in Lake St. Clair work were located by means of buoys 
which were placed in two lines. about 3,500 feet apart on either side of 
the proposed channel; the buoys were located with transit pointings and 
sextant angles. In the Lake Huron work the steamer was located every 
five minutes by transit pointings from two shore stations. 

When more minute surveys are required, such as making estimates for 
contract work, etc., more accurate location can be made by any of the 
usual methods. A specimen of the automatic record is shown at P, 
Fig. 2. This record was made on August 16, on which date the steamer 
Hancock was sunk by collision in Lake St. Clair. The drawing is an 
exact copy of the disk that was in the bathometer at the time of the sink- 
ing. The long straight line at Q was caused by the shock of the colli- 
sion. The clock was adjusted so as to cause the disk to make a complete 
revolution in one hour. During the hour preceding the sinking of the 
steamer, the channel had been crossed from buoy to buoy five times. 
The time of passing the buoys is shown by the short straight lines, which 
are made by the observer giving the bathometer a shake or jar so as to 
cause the pen to vibrate. During a portion of last season 22 miles of 
ship channel in Lakes Huron and St. Clair were sounded with a bath- 
ometer. The work was done rapidly and with a small working force. 
The bathometer was used in weather that was much too rough for the 
ordinary methods. The results were as accurate and satisfactory as those 
obtained in the ordinary methods. 



:4^ 



PLATE 1 



SKETCH 

Showing a St earner equipped with Bathometer. 



C Steam-chest and ^ir-com pressor 

VTank 

E Cable Drum 

Y Pipe 

G Sounding-line 

Yl6oundin^-line lyeighted with metal armor 




ELc«s>m.r,nM. 



ReoisLer for 

BATHOMETER, 

Model A. 



PLATE 2. 





PLATE 3 



Register for 

BATHOMETER 
Model B. 




HaJf Scale. 



.3J 



m 



LiBRf^R^ Ml!; 



028 



COWGRES^,^ \ 



106 ^^'^ 



# 









